def fib1(n):
    a=b=1
    for i in range(n-2):
        a ,b = b, a+b
    return b

def fib2(n):
    return 1 if n < 3 else fib2(n-1)+fib2(n-2)

def fib3(n,a=1,b=1):
    if n < 3:
        return b
    return fib3(n-1,b,a+b)

print(fib3(101))
